Sunol California Weather Forecast Discussion

117
FXUS66 KMTR 081557
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
857 AM PDT Wed Oct 8 2025
...New UPDATE, MARINE...
.KEY MESSAGES...
Updated at 152 AM PDT Wed Oct 8 2025
- Cooler and cloudier weather today
- Drizzle tonight through Thursday morning
- Light rain chances increase Friday through Saturday morning for
the North Bay, Bay Area and East Bay
&&
.UPDATE...
Issued at 855 AM PDT Wed Oct 8 2025
Extensive stratus cloud cover persists across the inland valleys
of the Bay Area and Central Coast this morning. The inland regions
are expected to gradually clear out through the afternoon hours,
but the coastal region could remain socked in through the day. The
forecast remains on track with no changes necessary.
DialH
&&
.SHORT TERM...
Issued at 152 AM PDT Wed Oct 8 2025
(Today and tonight)
A weak upper level low that has lingered off the central coast the
previous few days has begun evolving into an open wave overnight and
will eventually be absorbed by a deepening trough to our north later
this afternoon. The pattern change in motion this morning will
result in inland temperatures today that will be 5-15 degrees cooler
than yesterday and up to 5 degrees cooler along the coast. A weak
surface trough out ahead of the first of numerous upper level trough
axis` passing through our area the rest of the week, will bring
areas of drizzle tonight through Thursday morning.
&&
.LONG TERM...
Issued at 152 AM PDT Wed Oct 8 2025
(Thursday through Tuesday)
The persistent troughing pattern through the extended forecast
period will keep temperatures around or below normal well into next
week. Rain chances continue primarily for the North Bay Friday into
early Saturday, with thunderstorm chances around 5% or less Friday
afternoon. Consensus is good wrt the overall pattern through the
weekend. Extended deterministic guidance has poor consensus on
the potential for widespread wetting rainfall for the beginning of
next week. ECMWF/Canadian models have strong signal for rain,
while the GFS has little to no rain in our area for that same time
frame. The NBM is clearly leaning on the ECMWF/Canadian
solutions, which seems reasonable attm. The difference being the
GFS deepens an upper level disturbance farther inland, while the
ECMWF/Canadian indicate a more plausible deepening of the system
just offshore and push it south along the coast, giving it more
time to pick up moisture along the way.
&&
.AVIATION...
(12Z TAFS)
Issued at 536 AM PDT Wed Oct 8 2025
Nearly widespread MVFR and IFR CIGs are expected through much of the
morning. Cloud cover lifts and scatters into the late morning and
early afternoon. Leading to mostly VFR conditions across the region,
with the exception of STS, which will fail to clear. Expect moderate
to breezy winds through the afternoon and into the evening before
winds weaken and cloud cover builds in the North Bay and along the
immediate coast with chances for drizzle.
Vicinity of SFO...VFR through the TAF period. Expect passing low
clouds around the SF Bay through the morning that will thin out into
the afternoon as moderate southwest winds build. These winds look to
weaken and turn more southerly into the night as scattered mid-level
clouds build.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...MVFR CIGs linger into the afternoon before
eroding as winds increase. Cloud cover struggles to return into the
evening while winds reduce into the night.
&&
.MARINE...
(Today through Monday)
Issued at 855 AM PDT Wed Oct 8 2025
Gentle to moderate SW winds will gradually shift back to a NW
breeze Thursday. Winds will increase to a strong NW breeze late
Saturday, building rough seas by Sunday. Disturbed conditions
with periods of rain and gusty winds are expected early next week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT this afternoon for SF Bay N
     of Bay Bridge.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...Murdock
MARINE...Flynn
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NWS MTR Office Area Forecast Discussion